Biochemistry Module 6 Practice Exam

FAD acts as a redox cofactor that shuttles electrons (and associated protons) between molecules in enzyme-catalyzed reactions. In many dehydrogenases, the substrate donates two electrons and two protons to the oxidized FAD, forming FADH2. The enzyme then passes those electrons to the next carrier (for example, ubiquinone), regenerating FAD. This electron/hydrogen transfer role is why FAD is described as a carrier within the reaction. It’s not a detergent, it doesn’t donate phosphate groups to substrates, and it doesn’t bind DNA to regulate transcription.